Resistant TB from inappropriate treatment

Results of a systematic review and meta-analysis lend further weight to the role of inappropriate treatment in the rise of multidrug resistant tuberculosis (MDR-TB).

The Dutch and Swedish research team acknowledges it's generally accepted that inadequate treatment leads to resistance – but this group of researchers wanted even more evidence.

As reported online in the European Respiratory Journal, when Dr Marieke J. van der Werf of the KNCV Tuberculosis Foundation at The Hague and colleagues reviewed the literature, they found little information regarding treatment regimens, drug-resistance profile before treatment and at failure or recurrence, and genotype information at failure or recurrence.

The diagnosis of acquired MDR-TB required that the patient initially have a Mycobacterium tuberculosis strain that was susceptible to at least isoniazid or rifampicin, which became MDR-TB at the time of failure or disease-recurrence and with a genotype pattern identical to the initial strain at time of first diagnosis.

Study review

The researchers eventually identified and reviewed four studies, ranging in size from 233 to 2,901 patients.

Only two trials met the criteria for meta-analysis inclusion, however; these two involved more than 3,200 patients and showed that the risk of developing MDR-TB is 27-fold increased in patients who are prescribed an inappropriate treatment regimen.

The researchers added, "We believe that the risk that patients defined as having acquired MDR-TB were in fact re-infected with an identical strain that already was MDR-TB, is small."

"The new review provides evidence for the general opinion that the development of MDR-TB can be caused by treatment that is inadequate," the authors conclude.

They say "the evidence is based on the best quality studies available" and "If more studies become available the review and meta-analysis can be updated."

(Reuters Health, November 2011)

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Treating TB

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